Fast high performance liquid chromatography and ultraviolet–visible quantification of principal phenolic antioxidants in fresh rosemary

Evaluation of chlorogenic acid and carnosol for anti-efflux pump and anti-biofilm activities against extensively drug-resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa

Efflux pumps and biofilm play significant roles in bacterial antibiotic resistance. This study investigates the potential of chlorogenic acid (CGA) and carnosol (CL), as phenolic and diterpene compounds, respectively, for their inhibitory effects on efflux pumps. Among the 12 multidrug-resistant (MDR) strains of Staphylococcus aureus and Pseudomonas aeruginosa isolated from nosocomial skin infections, eight strains were identified as extensively drug resistant (XDR) using the disc diffusion method. The presence of efflux pumps in MDR strains of S. aureus and P. aeruginosa was screened using carbonyl cyanide-m-chlorophenylhydrazone. Between the 12 MDR strains of S. aureus and P. aeruginosa, 80% (4 out of 5) of the S. aureus strains and 85.7% (6 out of 7) of the P. aeruginosa strains exhibited active efflux pumps associated with gentamicin resistance. The checkerboard assay results, in combination with gentamicin, demonstrated that CGA exhibited a reduction in the minimum inhibitory concentration (MIC) for XDR S. aureus strain. Similarly, CL showed a synergistic effect and reduced the MIC for both XDR strains of S. aureus and P. aeruginosa. Flow cytometry was used to examine efflux pump activity at sub-MIC concentrations of 1/8, 1/4, and 1/2 MIC in comparison to the control. In XDR S. aureus, CGA demonstrated 39%, 70%, and 19% inhibition, while CL exhibited 74%, 73.5%, and 62% suppression. In XDR P. aeruginosa, CL exhibited inhibition rates of 25%, 10%, and 15%. The inhibition of biofilm formation was assessed using the microtiter plate method, resulting in successful inhibition of biofilm formation. Finally, the MTT assay was conducted, and it confirmed minimal cytotoxicity. Given the significant reduction in efflux pump activity and biofilm formation observed with CGA and CL in this study, these compounds can be considered as potential inhibitors of efflux pumps and biofilm formation, offering potential strategies to overcome antimicrobial resistance.

IMPORTANCE

In summary, CGA and CL demonstrated promising potentiating antimicrobial effects against XDR strains of Staphylococcus aureus and Pseudomonas aeruginosa, suggesting their probably potential as candidates for addressing nosocomial pathogens. They exhibited significant suppression of efflux pump activity, indicating a possible successful inhibition of this mechanism. Moreover, all substances effectively inhibited biofilm formation, while showing minimal cytotoxicity. However, further advancement to clinical trials is needed to evaluate the feasibility of utilizing CGA and CL for reversing bacterial XDR efflux and determining their efficacy against biofilms. These trials will provide valuable insights into the practical applications of these compounds in combating drug-resistant infections.

Exploring the Role of Phenolic Compounds in Chronic Kidney Disease: A Systematic Review

Chronic kidney disease (CKD) presents a formidable global health concern, affecting one in six adults over 25. This review explores the potential of phenolic compounds in managing CKD and its complications. By examining the existing research, we highlight their diverse biological activities and potential to combat CKD-related issues. We analyze the nutritional benefits, bioavailability, and safety profile of these compounds. While the clinical evidence is promising, preclinical studies offer valuable insights into underlying mechanisms, optimal dosages, and potential side effects. Further research is crucial to validate the therapeutic efficacy of phenolic compounds for CKD. We advocate for continued exploration of their innovative applications in food, pharmaceuticals, and nutraceuticals. This review aims to catalyze the scientific community's efforts to leverage phenolic compounds against CKD-related challenges.

A Validated HPLC-UV-ESI-IT-MS Method for the Quantification of Carnosol in Lepechinia mutica, a Medicinal Plant Endemic to Ecuador

The diphenolic diterpene carnosol was isolated from several species of the family Lamiaceae, including Lepechinia mutica, a medicinal plant endemic to Ecuador. The compound has exhibited high antioxidant, anti-inflammatory, antimicrobial, neuroprotective, and antifungal properties, as well as promising cytotoxicity against prostate, breast, skin, leukemia, and human colon cancer cell lines. In this paper, we developed and validated a simple, accurate, and reliable analytical HPLC-UV-ESI-IT-MS method, carried out on a C18 column, which is potentially suitable to quantify carnosol in plant extracts. The procedure complied with the established ICH validation parameters of analytical range (linearity in the range of 0.19-5.64 μg/g dried leaves; REAVERGE = 4.9%; R2 = 0.99907), analysis repeatability (RSD = 2.8-3.6%), intermediate precision (RSD = 1.9-3.6%), accuracy (estimated as % carnosol recovery in the range of 81 to 108%), and robustness. Finally, the LOD (0.04 µg/mg) and LOQ (0.19 μg/mg) values of carnosol/dried leaves were determined. Using this validated method, the content of carnosol in L. mutica was estimated to be 0.81 ± 0.04 mg/g of dried leaves (0.081%).

Multi-target neuroprotective effects of herbal medicines for Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease is the most common form of dementia, but its treatment options remain few and ineffective. To find new therapeutic strategies, natural products have gained interest due to their neuroprotective potential, being able to target different pathological hallmarks associated with this disorder. Several plant species are traditionally used due to their empirical neuroprotective effects and it is worth to explore their mechanism of action.

AIM OF THE STUDY

This study intended to explore the neuroprotective potential of seven traditional medicinal plants, namely Scutellaria baicalensis, Ginkgo biloba, Hypericum perforatum, Curcuma longa, Lavandula angustifolia, Trigonella foenum-graecum and Rosmarinus officinalis. The safety assessment with reference to pesticides residues was also aimed.

MATERIALS AND METHODS

Decoctions prepared from these species were chemically characterized by HPLC-DAD and screened for their ability to scavenge four different free radicals (DPPH^•, ABTS^•+, O₂^•‒ and ^•NO) and to inhibit enzymes related to neurodegeneration (cholinesterases and glycogen synthase kinase-3β). Cell viability through MTT assay was also evaluated in two different brain cell lines, namely non-tumorigenic D3 human brain endothelial cells (hCMEC/D3) and NSC-34 motor neurons. Furthermore, and using GC, 21 pesticides residues were screened.

RESULTS

Regarding chemical composition, chromatographic analysis revealed the presence of several flavonoids, phenolic acids, curcuminoids, phenolic diterpenoids, one alkaloid and one naphthodianthrone in the seven decoctions. All extracts were able to scavenge free radicals and were moderate glycogen synthase kinase-3β inhibitors; however, they displayed weak to moderate acetylcholinesterase and butyrylcholinesterase inhibition. G. biloba and L. angustifolia decoctions were the less cytotoxic to hCMEC/D3 and NSC-34 cell lines. No pesticides residues were detected.

CONCLUSIONS

The results extend the knowledge on the potential use of plant extracts to combat multifactorial disorders, giving new insights into therapeutic avenues for Alzheimer's disease.

Effect of Gamma Irradiation on the PLA-Based Blends and Biocomposites Containing Rosemary Ethanolic Extract and Chitosan

The irradiation of polymeric materials with ionizing radiation (γ-rays, X-rays, accelerated electrons, ion beams, etc.) may lead to disproportion, hydrogen abstraction, arrangements, degradation, and/or the formation of new bonds. The purpose of this paper is to evaluate the effect of gamma irradiation on some new poly(lactic acid) (PLA)-based blends and biocomposites, which is crucial when they are used for food packaging or medical purposes. The polymeric blends and biocomposites based on PLA and rosemary ethanolic extract (R) and poly(ethylene glycol) (PEG) (20 wt%) plasticized PLA, chitosan (CS) (3–6 wt%) and R (0.5 wt%) biocomposites were subjected to gamma irradiation treatment using three low γ-doses of 10, 20, and 30 kGy. The effect of irradiation was evaluated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), thermogravimetry (TG), chemiluminescence method (CL), migration studies, and antibacterial activity tests. It was found that in comparison with neat PLA, the gamma irradiation in the oxidative conditions of the PLA-based blends and biocomposites, causes modifications in the structure, morphology, and thermal properties of the materials depending on irradiation dose and the presence of natural additives such as rosemary and chitosan. It was established that under a gamma-irradiation treatment with dose of 10–20 kGy, the PLA materials showed minor changes in structure and properties being suitable for application in packaging and in addition after irradiation with such doses their antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium is improved.

Study on Thermal Behavior of Some Biocompatible and Biodegradable Materials Based on Plasticized PLA, Chitosan, and Rosemary Ethanolic Extract

Thermal characterization of some multifunctional environmentally friendly materials based on plasticized poly (lactic acid) (PLA)/chitosan (CS) and rosemary extract (R) previously obtained is presented. Differential scanning calorimetry (DSC) associated with other complex investigations such as chemiluminescence and coupled thermogravimetry (TG)/Fourier-transform infrared spectroscopy (FT-IR)/mass spectroscopy (MS) was performed in order to test both the thermal behavior and the biocomposition–property relationship. It was established that the rosemary ethanolic extract offers an efficient protection against thermoxidative degradation to the new developed plasticized PLA-based biocomposites which show good thermal properties, being suitable for both medical and food packaging applications.

Silica-Based Monolithic Columns as a Tool in HPLC-An Overview of Application in Analysis of Active Compounds in Biological Samples

Monolithic fillings used in chromatography are of great interest among scientists since the first reports of their synthesis and use were published. In the 20 years since silica-based monolithic columns were introduced into the commercial market, numerous papers describing their chromatographical properties and utility in various branches of industry and scientific investigations were presented. This review is focused on possible applications of commercially available silica-based HPLC monolithic columns in the analysis of biological samples.

Potential Albumin-Based Antioxidant Nanoformulations for Ocular Protection against Oxidative Stress

Amongst various drug administration methods, ophthalmic drug delivery has been a useful way for the treatment of eye-related diseases. However, therapeutic efficacy of ocular therapy for anterior or posterior eye segments through topical administration is considerably challenged by the number of anatomical and physiological barriers in the eyes affecting ocular bioavailability. In this respect, advanced biocompatible nanoformulations make it possible to improve drug delivery to the target sites and enhance ocular bioavailability of ophthalmic medicines. Various ocular diseases have been reported to be related to oxidative stresses in tissues, and polyphenolic compounds have been known for their antioxidant activities in various tissues, including the eyes. Despite drug efficacy, poor water solubility and intrinsic color of the compounds limit the drug’s inclusion into the development of ocular medicine. In the present study, we investigated the antioxidant protectant efficacy of rosmarinic or ursolic acid in the retinal epithelial cells, as compared to those of curcumin, by forming nanospheres with bovine serum albumin. Our results demonstrate that antioxidant-containing nanoformulations provide a significantly higher drug solubility and decreased ROS (reactive oxygen species) production in the retinal epithelial cells. Finally, we also found that albumin-based nanoformulations could improve bioavailability and increase antioxidant activity of rosmarinic or ursolic acid in the retina to be applied as efficient ocular protectant.

Antioxidant Activity Analysis for the Selection of Rosmarinus officinalis L

Rosmarinus officinalis L. presents a high genetic variability, which is reflected in the chemical composition of the different individuals, and consequently in its biological activity, including antioxidant capacity. The aim of the present research was to correlate the chemical composition of methanolic extracts of the dried leaves of eight rosemary accessions with their antioxidant activity for the selection of plants to optimize the use of rosemary. The eight samples examined, starting from a collection of more than 160 individuals selected by BOTANE Ltd, were cultivated at Illapel, north central Chile, using the same cultivation techniques. The free radical-scavenging capacity was tested by the ability of extracts to bleach the stable 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) and to inhibit superoxide anion (O2-) and hydroxyl radical (.OH) production. The metal chelating activity was estimated by the ferrozine assay. All extracts (1–8) contained high concentrations of carnosic acid, and to a minor extent rosmarinic acid, and exhibited antioxidant activity. However, extracts 7 and 8, containing 31.7 and 26.1% of carnosic acid, respectively, have shown a higher biological effect, confirming that the antioxidant activity of R. officinalis leaves is primarily related to this phenolic diterpene and suggesting that the measure of antioxidant activity could be considered a good method in the selection of this plant for its optimization. Interestingly, our experimental evidence also suggests that air pollution negatively influences the carnosic acid content. In fact, samples 3 and 4, with a low carnosic acid content, originated from a highly polluted metropolitan area of Santiago city.

Development and Validation of an Analytical Method Based on HPLC-ELSD for the Simultaneous Determination of Rosmarinic Acid, Carnosol, Carnosic Acid, Oleanolic Acid and Ursolic Acid in Rosemary

The safety, efficacy and stability of natural antioxidants have been the focus of research in the food industry, with the aim of rapidly analyzing and controlling the quality of rosemary and its extracts, a novel analytical method involving high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) was developed for the simultaneous determination of rosmarinic acid, carnosol, carnosic acid, oleanolic acid and ursolic acid in rosemary. Chromatographic separation was conducted with gradient elution mode by using a Zorbax SB-C18 column (4.6 mm × 250 mm, 5 μm) with mobile phases of methanol and 0.6% acetic acid. The drift tube temperature of ELSD was 70 °C, and the pressure of nebulizer nitrogen gas was 40 Psi. The method developed has high sensitivity (with limits of detection from 1.3 to 8.6 μg/mL), acceptable linearity over the tested concentrations (with correlation coefficients from 0.991 to 0.999), good repeatability (with intra- and inter-day CV less than 3.1% for all analytes) and satisfactory accuracy (with recovery between 95.5% and 100.8%). The method has been demonstrated as a powerful tool for the functional ingredients analysis and quality control of rosemary and its extracts in a cost- and time-effective manner.

Characterization by liquid chromatography-mass spectrometry and antioxidant activity of an ethanolic extract of Inula viscosa leaves

Inula viscosa (I. viscosa) is a common Mediterranean plant, well known for its content on bioactive molecules. The chemical composition of an ethanolic extract from I. viscosa leaves, growing in Algeria, was analysed by liquid chromatography coupled to photodiode array detection and electrospray ionization mass spectrometry (LC-DAD-ESI-MS/MS) operating in negative and positive mode. The methodology used revealed the presence of 51 compounds from which 47 were putatively identified, including 11 phenolic acids, 23flavonoids, one lignan and 12 terpenoids. Twenty-six of these compounds are described for the first time in I. viscosa. Antioxidant activity was measured using three different and complementary chemical assays: DPPH radical scavenging activity, oxygen radical absorbance capacity (ORAC) and hydroxyl radical scavenging capacity (HOSC). Results demonstrate that ethanolic leaf extract exhibit a high scavenging ability against DPPH (157.72 ± 6.45 μM TE/g DW), peroxyl (4471.42 ± 113.16 μM TE/g DW) and hydroxyl (630.10 ± 17.81 μM TE/g DW) radicals, indicating that I. viscosa can be a promising source of bioactive compounds.

A novel, simplified and stability-indicating high-throughput ultra-fast liquid chromatography method for the determination of rosmarinic acid in nanoemulsions, porcine skin and nasal mucosa

Currently, there is an increasing interest on the development of topical formulations containing rosmarinic acid (RA) due to its well-documented antioxidant activity. This study aimed to develop and validate a stability-indicating ultra-fast liquid chromatography (UFLC) method for the determination of RA in nanoemulsions, porcine skin and nasal mucosa intended to be applied in permeation/retention studies and for development of topical nanoemulsions. Chromatographic separation was carried out using a C18 column packed with 2.6 μm particle size in isocratic conditions using as mobile phase water:acetonitrile (83:17, v/v), acidified with 0.1% trifluoracetic acid (v/v), with a total time of analysis of 3.5 min and detection at 330 nm. RA analysis was specific in the presence of both non-biological (blank nanoemulsion and receptor fluid) and biological matrices (porcine ear skin and porcine nasal mucosa). No interference of degradation products of RA was verified after different stress conditions such as acidic, alkaline, oxidative, light exposure (UV-A and UV-C) and thermal demonstrating the method stability-indicating property. The analytical (0.1-10.0 μg·mL-1) and bioanalytical (0.5-10.0 μg·mL-1) linearity was proved by analysis of the calibration curves of RA and no matrix effect was observed. The method was sensitive, precise and accurate, and showed recovery higher than 85%. The method was considered robust as evaluated by a Plackett-Burman experimental design. In the validated conditions, the RA was determined in the nanoemulsions obtained by spontaneous emulsification procedure (1.007 ± 0.040 mg·mL-1), porcine ear skin (1.13 ± 0.19 μg·cm-2) and nasal mucosa (22.46 ± 3.99 μg·cm-2) after retention/permeation studies. Thus, a highly sensitive, simple, fast and stability-indicating method was developed for RA analysis during the development of topical nanoemulsions and bioanalytical assays in complex matrices.

Rosmarinus eriocalyx: An alternative to Rosmarinus officinalis as a source of antioxidant compounds

Rosmarinus eriocalyx is an aromatic evergreen bush endemic to Algeria where it is used as a condiment to flavour soups and meat and as a traditional remedy. In the present work we have analyzed for the first time the phenolic composition of polar extracts obtained from stems, leaves and flowers of R. eriocalyx by HPLC, and determined the antioxidant and antimicrobial effects by DPPH, ABTS, FRAP, ORAC and agar disc diffusion methods, respectively. Results showed that ethanolic extracts of leaves and flowers are a rich source of phenolic compounds, mainly rosmarinic acid, carnosic acid and carnosol that are the main responsible for the noteworthy antioxidant activity observed in the assays. This study showed that R. eriocalyx might be a spice to be included in the European food additive list and used as a preservative agent besides R. officinalis.

HPLC-DAD-MS/MS profiling of standardized rosemary extract and enhancement of its anti-wrinkle activity by encapsulation in elastic nanovesicles

The anti-wrinkle activity of defatted rosemary extract (DER) was assessed, and its effect was optimized by encapsulation in transferosomes (TFs). DER was standardized to a rosmarinic acid content of 4.58 ± 0.023 mg% using reversed-phase high performance liquid chromatography (Rp-HPLC), and its components were identified by HPLC-diode array detection-tandem mass spectrometry. In vitro free radical scavenging assays showed DER had high free radical scavenging activity against 2,2-diphenyl-2-picryl hydrazyl, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and superoxide radicals. DER also inhibited bleaching of β-carotene with high Fe(III) and Fe(II) chelating ability. In vivo anti-wrinkle activities of topically applied DER (20, 50, and 100 mg) and a TF formulation (TF4, 20 mg of DER) were evaluated in UVB-irradiated mice using a wrinkle scoring method, metalloproteinase (MMP) expression, and histopathology. Among the nanovesicles, TF4 was the most deformable, and had an acceptable size and encapsulation efficiency and enhanced permeation of DER through rat skin compared with unencapsulated DER. DER (50 and 100 mg) and TF4 significantly inhibited MMP-2 and MMP-9 expression and improved wrinkle scores. DER and TF4 moderately decreased epidermal thickness without pigmentation. DER is a potent natural antioxidant for combating skin aging. Moreover, encapsulation of DER in TFs will enhance its skin permeation and anti-wrinkle activity.

Synthesis, antiproliferative and antifungal activities of 1,2,3-triazole-substituted carnosic Acid and carnosol derivatives

Abietane diterpenes exhibit an array of interesting biological activities, which have generated significant interest among the pharmacological community. Starting from the abietane diterpenes carnosic acid and carnosol, twenty four new triazole derivatives were synthesized using click chemistry. The compounds differ in the length of the linker and the substituent on the triazole moiety. The compounds were assessed as antiproliferative and antifungal agents. The antiproliferative activity was determined on normal lung fibroblasts (MRC-5), gastric epithelial adenocarcinoma (AGS), lung cancer (SK-MES-1) and bladder carcinoma (J82) cells while the antifungal activity was assessed against Candida albicans ATCC 10231 and Cryptococcus neoformans ATCC 32264. The carnosic acid γ-lactone derivatives 1–3 were the most active antiproliferative compounds of the series, with IC₅₀ values in the range of 43.4–46.9 μM and 39.2–48.9 μM for MRC-5 and AGS cells, respectively. Regarding antifungal activity, C. neoformans was the most sensitive fungus, with nine compounds inhibiting more than 50% of its fungal growth at concentrations ≤250 µg∙mL⁻¹. Compound 22, possessing a p-Br-benzyl substituent on the triazole ring, showed the best activity (91% growth inhibition) at 250 µg∙mL⁻¹ In turn, six compounds inhibited 50% C. albicans growth at concentrations lower than 250 µg∙mL⁻¹.

Variations of Carnosic acid and Carnosol Concentrations in Ethanol Extracts of Wild Lepechinia salviae in Spring (2008–2011)

Ethanol extracts from dried leaves of wild Lepechinia salvia (Lindl) Epling, collected during the flowering period (September-November), contained 15% to 25% carnosic acid and 2 to 8% carnosol, depending on the month of collection. The highest concentration of carnosic acid in extracts was in October, while carnosol concentration had a peak in September, which suggests that it is not a product of carnosic acid oxidation. A comparison of extracts obtained in September 2008 to 2011 shows that the production of both abietanes increased in years with less winter rainfall and higher temperatures, which induced an early blooming. EC50values in DPPH radical scavenging and antiproliferative (CCRF-CEM tumor cells) bioassays confirm that the high bioactivity of the extracts of rosemary, sage and L. salviae does not arise only from carnosol and carnosic acid. The cytotoxic activity was significantly higher in extracts of L. salviae, probably due to water stress differences between the cultivars and the wild species. These results correlate well with the close phylogenetic relationship between the three species, and their similar medicinal uses.

Preparative separation and purification of rosmarinic acid from perilla seed meal via combined column chromatography

In this study, the preparative separation and purification of rosmarinic acid (RA) from perilla seed meal (PSM), which is a by-product of edible oil production, was achieved using combined column chromatography over macroporous and polyamide resins. To optimize the RA enrichment process, the performance and separation characteristics of nine selected macroporous resins with different chemical and physical properties were investigated. SP825 resin was the most effective: the content of RA increased from 0.27% in the original extract to 16.58% in the 50% ethanol fraction (a 61.4-fold increase). During further purification treatment on polyamide resin, 90.23% pure RA could be obtained in the 70% ethanol fraction. RA with a higher purity (>95%) could also be easily obtained using one crystallization operation. The proposed method is simple, easily operated, cost-effective, and environmentally friendly and is suitable for both large-scale RA production and waste management.

Concentration of antioxidant polyphenols from Thymus capitatus extracts by membrane process technology

Thymus capitatus is a Mediterranean plant characterized by its antioxidant polyphenols of which the most known are the carnosic and rosmarinic acids. In this way, this study aims to concentrate these acids by membrane processes. The thyme essential oil composition was established by capillary GC-MS and 27 components were identified representing 98.93%± 1.97% of total oils. The antioxidant test for permeate and retentate of methanolic and aqueous extract were determined using 3 types of membranes. The results showed that the synthetic NF membrane is able to trap and concentrate phenolic compounds in the retentate much better than the NF commercial and UF synthetic membrane. The results of the total phenolic content (TPC) showed a significant value of the polyphenol content present in the aqueous extract with 175.53 mg Gallic Acid Equivalents (GAE)/g of extract. The spectrum of the aqueous extract of Thymus capitatus showed the presence of 3 visible peaks, the 1st one at 217 nm corresponding to the carnosic acid, the 2nd one at 277 nm for essential oils, and the last one at 326 nm attributed to the rosmarinic acid. The commercial membrane NF-DK succeeded to concentrate rosmarinic acid and can be considered as a stage towards the concentration of this product with a high added value.

Storage method, drying processes and extraction procedures strongly affect the phenolic fraction of rosemary leaves: an HPLC/DAD/MS study

The Rosmarinus officinalis L. is widely known for its numerous applications in the food field but also for the increasing interest in its pharmaceutical properties. Two groups of compounds are mainly responsible for the biological activities of the plant: the volatile fraction and the phenolic constituents. The latter group is mainly constituted by rosmarinic acid, by a flavonoidic fraction and by some diterpenoid compounds structurally derived from the carnosic acid. The aim of our work was to optimize the extractive and analytical procedure for the determination of all the phenolic constituents. Moreover the chemical stability of the main phenols, depending on the storage condition, the different drying procedures and the extraction solvent, have been evaluated. This method allowed to detect up to 29 different constituents at the same time in a relatively short time. The described procedure has the advantage to being able to detect and quantify several classes of compounds, among them numerous minor flavonoids, thus contributing to improving knowledge of the plant. The findings from this study have demonstrated that storing the raw fresh material in the freezer is not appropriate for rosemary, mainly due to the rapid disappearing of the rosmarinic acid during the freezing/thawing process. Regarding the flavonoidic fraction, consistent decrements, were highlighted in the dried samples at room temperature if compared with the fresh leaf. Rosmarinic acid, appeared very sensitive also to mild drying processes. The total diterpenoidic content undergoes to little changes when the leaves are freeze dried or frozen and limited losses are observed working on dried leaves at room temperature. Nevertheless it can be taken in account that this fraction is very sensitive to the water presence during the extraction that favors the conversion of carnosic acid toward it oxidized form carnosol. From our findings, it appear evident that when evaluating the phenolic content in rosemary leaves, several factors, mainly the type of storage, the drying process and the extraction methods, should be carefully taken into account because they can induce partial losses of the antioxidant components.

Stability studies on trans-rosmarinic acid and GC-MS analysis of its degradation product

The stability of trans-rosmarinic acid (trans-RA, an important phenolic compound with anti-oxidant, anti-inflammatory, anti-bacterial, and anti-viral properties) exposed to different stress conditions (daylight, higher temperatures, different solvents, and humidity) was investigated. Gas chromatography-mass spectrometry (GC-MS) was used to analyse the degraded samples, and structural identification of degradation products was assigned based upon MS fragmentation pattern. The GC-MS method was validated in terms of linearity, precision as repeatability, accuracy, limit of detection (LOD), limit of quantitation (LOQ) and recovery. The stability experiments were performed on pure trans-RA and on trans-RA present in commercially available rosemary extract. The cis-isomer of RA was the only degradation product. The results showed that trans-RA was readily isomerized into its cis-form within a few hours when dissolved in ethanol, methanol or tetrahydrofuran, and exposed to darkness or daylight at different temperatures. Isomerization took place to a greater extent in protic than in aprotic solvents. Trans-RA in the solid state was found to be stable for up to three months under all tested conditions. The described GC-MS method was also applied to the determination of trans-RA in eight different species of Lamiaceae family.

Recent developments in the HPLC separation of phenolic compounds

Phenolic compounds represent a class of highly complex naturally occurring molecules that possess a range of beneficial health properties. As a result, considerable attention has been devoted to the analysis of phenolics in a variety of samples. HPLC is the workhorse method for phenolic separation. However, conventional HPLC methods provide insufficient resolving power when faced with the complexity of real-world phenolic fractions. This limitation has been traditionally circumvented by extensive sample fractionation, multiple analysis methods and/or selective detection strategies. On the other hand, there is an increasing demand for improved throughput and resolving power from the chromatographic methods used for phenolic analyses. Fortunately, during the last decade, a number of important technological advances in LC have demonstrated significant gains in terms of both speed and resolution. These include ultra high-pressure liquid chromatography (UHPLC), high-temperature liquid chromatography (HTLC), multi-dimensional separations as well as various new stationary phase chemistries and morphologies. In recent years, these technologies have also found increasing application for phenolic analysis. This review seeks to provide an updated overview of the application of recent advances in HPLC to phenolic separation, with the emphasis on how these methodologies can contribute to improve performance in HPLC analysis of phenolics.

Gastroprotective effect of carnosic acid gamma-lactone derivatives

Carnosic acid (1) has been shown to possess gastroprotective activity in vitro and in vivo. However, little is known of the gastroprotective effect or cytotoxicity of carnosic acid gamma-lactone (3). To determine structure-activity relationships, a series of 17 esters of 3 were prepared including aliphatic, aromatic, and heterocyclic derivatives. Also, two units of 3 were coupled with succinic and phthalic acid as linkers. The compounds were assessed for their gastroprotective effect in the HCl/EtOH-induced gastric lesions model in mice and for cytotoxicity in human lung fibroblasts, human adenocarcinoma AGS cells, and Hep G2 hepatocellular carcinoma cells. At a single oral dose of 40 mg/kg, the gastroprotective effect increased moderately with the length of the alkyl chain. The best effects were observed for the butyrate (9) and chloroacetate (6) derivatives. Activity of fatty acid esters increased with chain length but decreased with unsaturation. The best gastroprotective effect, with lowest cytotoxicity, was found for the palmitate (11) and oleate (12) derivatives.

High-performance liquid chromatography method for determination of carnosic acid in rat plasma and its application to pharmacokinetic study

A sensitive and reproducible high-performance liquid chromatography method with ultraviolet detection (UV) was developed for the determination of carnosic acid (CA) in rat plasma. After simple acidification and liquid-liquid extraction of plasma samples using gemfibrozil as an internal standard, the supernatant was evaporated to dryness under a gentle stream of nitrogen. The residue was reconstituted in 200 microL before being injected into the chromatographic system. The analysis was performed on a C(18) column protected by an ODS guard column using acetonitrile-0.1% phosphoric acid (55:45, v/v) as mobile phase, and the wavelength of the UV detector was set at 210 nm. The calibration curve was linear over the range of 0.265-265.0 microg/mL with a correlation coefficient of 0.9997. The recovery for plasma samples of 0.530, 13.25, 132.5 and 265.0 microg/mL was 72.2, 87.9, 90.4 and 94.7%, respectively. The intra-day and inter-day relative standard deviations for the measurements of quality control samples were less than 3.1%. The stability of the plasma samples was also validated. This method was successfully used to study the pharmacokinetics and bioavailability of CA in rats.

Light-induced vegetative anthocyanin pigmentation in Petunia

The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins and flavonols, as well as the activation of the early and late flavonoid biosynthetic genes required for flavonol and anthocyanin production. Pigmentation in Lc petunia only occurred under conditions which normally induce a modest amount of anthocyanin to accumulate in wild-type Mitchell petunia [Petunia axillaris x (Petunia axillaris x Petunia hybrida cv. 'Rose of Heaven')]. Anthocyanin pigmentation in Lc petunia leaves appears to screen underlying photosynthetic tissues, increasing light saturation and light compensation points, without reducing the maximal photosynthetic assimilation rate (A(max)). In the Lc petunia system, where the bHLH factor Leaf colour is constitutively expressed, expression of the bHLH (Lc) and WD40 (An11) components of the anthocyanin regulatory system were not limited, suggesting that the high-light-induced anthocyanin pigmentation is regulated by endogenous MYB transcription factors.

On-line coupled dynamic sonication-assisted extraction-liquid chromatography for the determination of phenolic acids in Lamiaceae herbs

A fast and efficient on-line coupled dynamic sonication-assisted extraction-liquid chromatography (DSAE-LC) method was developed for the determination of phenolic acids in basil, oregano, rosemary, sage, spearmint and thyme. The extraction and chromatography were coupled via a solid-phase trap filled with strong anion exchange material. The relative standard deviations (RSDs) for the retention times were less than 0.4% and those for the peak heights less than 3% except for gallic acid (RSD 1.2% for the retention times and 11% for the peak heights). Limits of detection were below approximately 3ng.

Determination of phenolic content and antioxidant activity of extracts obtained from Rosmarinus officinalis' calli

Rosmarinus officinalis is widely found in the lands of Aegean and Mediterranean regions of Turkey. Stem explants of very young shoots were cultured in both woody plant medium (WPM) and Murashige and Skoog (MS) media supplemented with 7g/L agar, 30g/L sucrose, and 1 and 3mg/L naphthaleneacetic acid (NAA) for callus initiation. Induced calli were subcultured 4 times with intervals of 7-10 days. MS medium supplemented with 1mg/L NAA proved to be the best medium for the production of callus (65.0%) among the samples tested. The lyophilized calli were subjected to solvent extraction. Active constituents of 8 calli extracts were analyzed by HPLC, and rosmarinic acid (RA) was determined to be the primary compound. Calli cultivated in WPM supplemented with 1mg/L NAA and extracted at 50 degrees C, yielded the highest amount of RA (34.4mg/g dry weight). Moreover, antioxidant activity of calli extracts was determined using a number of in vitro assays, including total phenol assay, DPPH radical scavenging activity (RSA), and trolox equivalent antioxidant capacity (TEAC). On the basis of the current findings, we conclude that WPM supplemented with 1mg/L NAA yields higher phenolic content as well as higher antioxidant activity.

Antioxidant activity and phenolic composition of Lavandin (Lavandula x intermedia Emeric ex Loiseleur) waste

The phenolic content of lavandin waste obtained after the distillation of essential oils for the perfume industry was investigated to find an alternative use for this material. The antioxidant activity of different fractions as well as their total phenolic content were evaluated by different methods. Twenty-three phenolic compounds were identified by liquid chromatography coupled to ionspray mass spectrometry (LC/MS/MS), including phenolic acids, hydroxycinnamoylquinic acid derivatives, glucosides of hydroxycinnamic acids, and flavonoids, none of which have previously been reported in lavandin waste. Some structure-activity relationships were proposed by relating the type of scavenging activity of different fractions with the identified phenolic compounds. Contents of representative phenolic acids of Lamiaceae (chlorogenic and rosmarinic) were evaluated by high performance liquid chromatography-diode array detection (HPLC-DAD) and compared with those of other plant species.

Characterization of two unknown compounds in methanol extracts of rosemary oil

In this study, two unknown compounds in rosemary oil, containing 3% carnosic acid and 0.3% carnosol, were identified and characterized. After methanol extraction, purification, and analysis by reversed-phase HPLC and LC-MS, a recovery of 92% (+/-8%) of carnosic acid was obtained, but no carnosol was found. However, two unknown compounds with a molecular weight of 330.2 and 302.2 were consistently detected. From additional LC-MS-MS, (1)H NMR, and elemental analyses, it became clear that the first compound (M(w) = 330.2) could not be carnosol. It was hypothesized that it originated from the breakdown of the intramolecular bond of carnosol, followed by the addition of a water molecule. Possibly, an unsaturated double bond was formed after dehydration. Assuming that this compound was an intermediate in the conversion to rosmanol, the second unknown compound (M(w) = 302.2) may have resulted from the breakdown of the intramolecular bond of rosmanol. Similarly, an unsaturated double bond may have been formed. After splitting off carbon oxide, a detectable molecule with a molecular weight of 302.2 was observed.

On-line coupling of dynamic microwave-assisted extraction with high-performance liquid chromatography for determination of andrographolide and dehydroandrographolide in Andrographis paniculata Nees

A novel technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with high-performance liquid chromatography (HPLC) through a flow injection interface has been developed for determination of andrographolide and dehydroandrographolide in Andrographis paniculata Nees. A TM(010) microwave resonance cavity built in the laboratory was applied to concentrating the microwave energy. An extraction vessel was placed in microwave irradiation zone. The extraction was performed in a recirculating system. When a number of extraction cycles were completed, the fractional extract (20muL) was driven to the analytical column by 65% aqueous methanol and was measured by diode array detector (DAD) at 225nm. The optimized extraction conditions are follows: extraction solvent 60% aqueous methanol; microwave forward power 80W; extraction time 6min; extraction solvent flow-rate 1.0mLmin(-1). The detection and quantification limits obtained are 0.5 and 1.7microgmL(-1) for andrographolide and 0.6 and 1.9microgmL(-1) for dehydroandrographolide, respectively. The within-day and between-day precision (RSD) are 2.1% and 3.7% for andrographolide and 1.7% and 4.1% for dehydroandrographolide, respectively. Mean recoveries for andrographolide and dehydroandrographolide are 97.7% and 98.7%, respectively. Compared with ultrasonic extraction used in the Chinese pharmacopoeia, the proposed method was demonstrated to obtain higher extraction yield in a shorter time. In addition, only small quantities of solvent (5mL) and sample (10mg) were required.

Application of monolithic (continuous bed) chromatographic columns in phytochemical analysis

One and a half decade passed since the pioneering work on synthesis and application of non-particulate monolithic stationary phases for liquid chromatography was published by S. Hjertén et al. [S. Hjertén, J.L. Liao, R. Zhang, J. Chromatogr. 473 (1989) 273]. This technique attracted much interest and effort of the researchers developing chromatographic methods and designing chromatographic stationary phases due to several generic qualities of the monolithic (continuous bed) technique. Advantages include: flexibility of the technique in sense of chemistries and functional compositions of the resultant stationary phases; low separation impedance (ratio of pressure drop and efficiency) of monolithic columns; compatibility with micro and nanoformat separations; low time and labour consumption and cost-efficiency. Not surprisingly, these materials attracted interest from phytochemists as plants constitute a complex matrix. However to date, not many successful studies were published in the area of monolithic materials for solving plant metabolomics problems or substituting common particulate materials with monolithic stationary phases in phytochemical analysis. This paper provides an overview.